Abstract

People involved in health care, either as providers or recipients, often need to make choices between different interventions,
actions and strategies. They need evidence on the effects of the interventions and this should ideally come from systematic
reviews of randomised trials. This paper describes three large, landmark trials from the last two decades, highlighting benefits
to health and well being of this type of research. The International Subarachnoid Aneurysm Trial (ISAT) randomised patients
with a subarachnoid haemorrhage to neurosurgical clipping versus endovascular coiling. It recruited 2143 patients and found
a benefit of 24% for coiling in the primary outcome of death or dependency at one year, leading to substantial changes in
practice and savings lives and resources. The MidU trial compared two different models of maternity care, midwifery- versus
consultant-led care in north east Ireland. Pregnant women were only able to access the midwife-led units (MLUs) through the
randomised trial. These were the first MLUs in Ireland and a total of 1653 women joined the study, which concluded that this
form of care was as safe as consultant-led care, and associated with less intervention during labour and delivery. In the
late 1990s, steroids were widely used in the treatment of patients with head injury. The CRASH trial was designed with a target
sample size of 20,000 patients to detect reliably a reduction in mortality from 15% in the placebo group to 13% in the group
allocated the steroid, methylprednisolone. However, it was stopped early when 10,000 patients had been randomised from 239
hospitals in 49 countries, and it was clear that corticosteroids did more harm than good. The analyses showed that 25.7% of
patients allocated corticosteroids had died by six month compared to 22.3% in the placebo group (relative risk: 1.15, 1.07–1.24,
p=0.0001). Randomised trials and, in particular, systematic reviews of randomised trials provide reliable and robust estimates
of the relative effects of different interventions. They are key sources of information for evidence based health care and
well–informed choices.